xtensor-example.R

// [[Rcpp::depends(xtensor)]]

#include <numeric>
#include "xtensor/xmath.hpp"
#include "xtensor-r/rarray.hpp"
#include <Rcpp.h>

using namespace Rcpp;

// [[Rcpp::plugins(cpp14)]]

// [[Rcpp::export]]
double sum_of_sines(xt::rarray<double>& m)
{
  auto sines = xt::sin(m);
  return std::accumulate(sines.cbegin(), sines.cend(), 0.0);
}


// You can include R code blocks in C++ files processed with sourceCpp
// (useful for testing and development). The R code will be automatically
// run after the compilation.
//

/*** R
sum_of_sines(42)
*/

Running sourceCpp (or clicking Source in RStudio) gives:

> Rcpp::sourceCpp('~/Desktop/Untitled.cpp')

> sum_of_sines(42)
[1] -0.9165215

With the "attribute" defined at the top of the code, RStudio actually is able to recognize that I want to use xtensor and code completes things for me.

Without it, that code completion is not recognized

Ugh I think it's a windows/C++ thing blergh

@alexpghayes

I think this is heavily related to your closed issue here. I am absolutely no expert but maybe they need to use PKG_CPPFLAGS instead of PKG_CXXFLAGS in this file. I only say that because that seems to be what Rcpp does here?

It just looks like it's either not finding your C++14 or it was called incorrectly or something.